Animal pets, such as dogs and cats, like their human counterparts, are subject to dental health problems. These problems can be traced to the formation of bacterial plaque that forms on the exterior surface of teeth. Plaque is an invisible, sticky film of bacteria, salivary proteins and polysaccharides that are not easily washed away. Plaque is now generally recognized as the main culprit of poor oral health. Bacteria that produce the acid for the caries process are held to the tooth surface by the plaque matrix as well as other bacteria which cause redness and swelling (gingivitis). The presence of these bacteria, if left untreated, may spread to cause malodor, periodontal disease, gingival pockets and bone loss.
Dental calculus, or tartar, is the result of the thickening and hardening (mineralization) of dental plaque. Tartar, which is not easily removed, accumulates on the tooth surface, mainly at the gingival margin opposite the salivary glands. It is a hard mineral deposit containing predominantly calcium and phosphate, very tightly bound to the tooth surface. Once it is formed, tartar is virtually impossible to remove except by a dental professional. Tartar can become unsightly if growth is left unimpeded, and elimination is desirable as the porous surface of the calculus will be covered by a thin layer of unmineralized plaque that can cause constant irritation of the gums and can trigger other problems once calculus is formed below the gum line.
A variety of products have been manufactured to provide animal pets with objects to chew or gnaw. They are intended to provide the pet with exercise for the teeth to maintain a healthy condition satisfying a need that arose when the natural pet food, raw meat, was replaced with processed pet foods. Rawhide strips knotted on the ends to resemble bones, for example, provide abrasion for cleaning teeth by removing tartar and massaging the gums, which is not provided by the typical canine dog food.
U.S. Pat. No. 5,827,565 discloses that most dogs enjoy chewing on various objects, although preferences vary as to the desired hardness of those objects. Some dogs like to chew on very hard materials such as cow bones, wood, nylon, and the like. Some dogs, due to their age, may not be able to chew on very hard substances. Young dogs may have insufficiently developed teeth, while older dogs may have diseased gums or may have lost some of their teeth.
The prior art is therefore replete with examples of hard chews, soft chews, indigestible chews, and digestible chews. For example, Applicant's assignee, TFH Publications, Inc. has previously developed an edible dog chew that is wholly digestible, nutritious and maintains a texture or hardness which is individually adjustable, by application of heat to suit a wide variety of preferences or needs. Such dog chews utilize a mixture of primarily casein and are described in U.S. Pat. Nos. 5,200,212 and 5,240,720.
In Applicant's U.S. Pat. No. 5,827,565 there is disclosed a process for making a heat expandable dog chew comprised primarily of injection molded potato starch granules and an attractant. Attractants recited include chicken powder, liver powder, ham, turkey, beef and/or fish. Natural vegetable additives such as spinach or carrots may also be added.
In Applicant's U.S. Pat. No. 6,126,978, which is a continuation-in-part of U.S. Pat. No. 5,827,565, there is disclosed a dog chew having natural fruit flavor to increase the dog's appetite for such chew. The preferred form of such edible chew maintained the basic ingredient of a heat-expandable starch; such as potato starch.
Attention is also directed to the following U.S. patents commonly owned by the assignee herein: U.S. Pat. No. 5,476,069 entitled “Molded Rawhide Chew Toy”; U.S. patent application Ser. No. 08/923,070 filed Sep. 3, 1997 entitled “Vegetable Based Dog Chew” now U.S. Pat. No. 6,093,427; U.S. patent application Ser. No. 08/738,423 filed Oct. 25, 1997 entitled “Edible Dog Chew” now U.S. Pat. No. 5,827,565; U.S. patent application Ser. No. 08/784,834 filed Jan. 17, 1997 entitled “Carrot-Based Dog Chew” now U.S. Pat. No. 5,941,197; U.S. patent application Ser. No. 09/114,872 filed Jul. 14, 1998 entitled “Heat Modifiable Edible Dog Chew” now U.S. Pat. No. 6,180,161; U.S. patent application Ser. No. 09/138,804 filed Aug. 21, 1998 entitled “Improved Edible Dog Chew” now U.S. Pat No. 6,126,978; U.S. patent application Ser. No. 09/116,070 filed Jul. 15, 1998 entitled “Wheat & Casein Dow Chew With Modifiable Texture” now U.S. Pat. No. 6,110,521; U.S. patent application Ser. No. 09/116,555 filed Jul. 15, 1998 entitled “Heat Modifiable Peanut Dog Chew” now U.S. Pat. No. 6,093,441; U.S. patent application Ser. No. 09/227,767 filed Jan. 8, 1999 entitled “Method of Molding Edible Starch” now U.S. Pat. No. 6,159,516; and U.S. Pat. No. 6,200,616 entitled “Animal Chew”.
U.S. Pat. No. 5,407,661 entitled “Pet Chew Product Having Oral Care Properties” discloses an edible pet chew product having a flexible cellular matrix in which is contained cellulosic fibrous material such as corn cob fractions which are described as having a mechanical cleansing function when chewed by a pet.
U.S. Pat. No. 5,711,254 entitled “Dog Chew Toy” discloses a chew toy for dogs formed of a length of composite rope having an inner core defined by strands of twisted threads of natural plant or synthetic fibers and a soft outer shell defined by a plurality of strands of soft cotton threads twisted about the inner core. The inner core is said to be less water absorbent than the outer shell to promote drying of the toy when wetted with dog saliva to inhibit bacteria growth.
Other earlier examples of chew products are disclosed in U.S. Pat. No. 3,871,334 to Axelrod (nylon substrate containing liquid flavor and odor components), U.S. Pat. No. 4,771,733 to Axelrod (polyurethane toy containing aqueous-based flavor and odor components), and U.S. Pat. Nos. 4,557,219 and 4,513,014 to Edwards (use of flavorings in a molded polyurethane dog chew).
European Patent 0 272 968 B1 discloses a chewable product for dogs and other domestic animals wherein certain aqueous solutions of oral care agents, e.g., sodium fluoride (anti-caries agent), sodium benzoate (anticalculus agent) and bromochlorophene (antimicrobial/antiplaque agent) are used to soak rawhide, beef tendon, or ligament. The solution treated product is then dried whereby the oral care agents are absorbed into the surface of the product.
U.S. Pat. Nos. 5,000,940 and 5,000,943 disclose baked dog biscuits containing an inorganic pyrophosphate Salt, e.g., tetrasodium pyrophosphate, which when chewed and/or eaten by dogs cause a reduction in tartar accumulations on their teeth.
As can be seen from the above, the prior art has developed examples of hard chews, soft chews, indigestible chews; and digestible chews. All of these prior art animal chews rely on the animal's chewing to cause the bone to contact the teeth. Accordingly, a need remains to advance the design of the prior art products to improve the efficiency of a given chew toy to enhance the dental hygiene requirements of the animal.
There is, therefore, a need in the pet food field for an edible animal chew toy that can rub between the sides of the animal's teeth and massage the gums of the animal to reduce the build up of plaque and loss of teeth due to periodontal disease.